On my little site it is common practice to install tails through steel gland plates; tails vary in size from 16mm to 300mm.
The tails are installed via bushed single entry holes
When I mentioned electromagnetic effects others insist that this is normal practice and nothing gets the slightest bit warm.
So while in the UK if we came across an installation installed in this manner it would be a pointing finger and a sharp intake of breath.
So is ferrous enclosures electromagnet effects really the end of the plant as we know and therefore is this regulation required.

I tend to agree - I know of a metal-clad DB where the tails have been taken through individual 20mm holes - L2 usually carries close to 70A and while the tail itself is slightly warm to the touch, the steel is quite cool.

Certainly the instance that c.p.c.s are taken through the same hole seems unjustifiable - any intended effect is surely lost by the inevitable interconnection of exposed- and extraneous- parts downstream - and the exception only for g/y run alongside SWA just makes it all seem inconsistent. (521.5.1).

I can only express concern.
Many years ago I was a member of the emergency call out team (before the days when you had to go on a course to blow your nose!!).
I was called out to a no supply in a small office block in a nearby town centre. It was winter and chilly.
On arrival I found a neat set of 3 phase tails from the meter, passing through 5 holes in a a 4x4 metal trunking and feeding a selection of single phase and 3 phase boards. The paint on the trunking was charred around 2 phases and the neutral holes. The cable insulation had melted and obviously blown 2 of the three main fuses as everything 'touched'.
I managed to 'repair' (OK, slight rewire/bodge) to get everything operational again. The contracting dept. (those days, the electricity boards did everything) attended a couple of days later to sort out the damage properly.

Until you have seen it, like me, you would not believe the damage caused.

Of course, nowadays, I wouldn't b allowed within a mile of this situation as I haven't been on a course!

So is ferrous enclosures electromagnet effects really the end of the plant as we know and therefore is this regulation required.

It can be the end of the planet for sure - if in the wrong place.

A combination of sheath circulating currents and light, mild steel glandplates on a set of tails between a 1250kVA taransformer and LV switchboard (groups of 500mm2 AWA Singles) genetated enough heat to strip the paint from the glandplates and actually melt the cable gland shrouds - the heat in the main switch terminal chamber was over 105C and the insulation was virtually dripping off the conductors.

You may have been lucky through a combination of cable disposition and thickness of steel plates but if you chuck enough amps through the system the plates will get hot - very hot in fact.

Based on the science and my direct observation, the regulation is very much required.

My experiences designing for jobs in your corner of the globe, getting the message across to contractors is difficult - everyone has a story of how they did just that previously with no problems - until it all goes horribly wrong of course - - the phrase " I hate to say I told you so, but ................." is oft heard

Old and unqualified eh - it's what we used to call "Old Skool" - area board trained apprentice with a good chunk of common sense - there's a place for you still, Norm - the new breed don't know everything just yet - even if they think they do

Old and unqualified eh - it's what we used to call "Old Skool" - area board trained apprentice with a good chunk of common sense - there's a place for you still, Norm - the new breed don't know everything just yet - even if they think they do

Regards

OMS

OMS what is this common sense you speak oft of? Can I get it on a course? Does it have an expiry date and stupid expensive refresher courses?

Old and unqualified eh - it's what we used to call "Old Skool" - area board trained apprentice with a good chunk of common sense - there's a place for you still, Norm - the new breed don't know everything just yet - even if they think they do

Regards

OMS

OMS what is this common sense you speak oft of?

I may speak oft of it but it's still a rare thing

Can I get it on a course? Does it have an expiry date and stupid expensive refresher courses?

Well, not really - you can gain information from a course - it's your personal evaluation that turns it into knowldge and gives you an insight into where you can and can't apply that knowledge - that's the common sense bit

Otherwise I'll think I'll pass.

Pity - not everything needs a brand to be valuable, don't pass up the opportunity to pick up things by osmosis - it's worth a lot

Old and unqualified eh - it's what we used to call "Old Skool" - area board trained apprentice with a good chunk of common sense - there's a place for you still, Norm - the new breed don't know everything just yet - even if they think they do

Regards

OMS

OMS what is this common sense you speak oft of?

I may speak oft of it but it's still a rare thing

Can I get it on a course? Does it have an expiry date and stupid expensive refresher courses?

Well, not really - you can gain information from a course - it's your personal evaluation that turns it into knowldge and gives you an insight into where you can and can't apply that knowledge - that's the common sense bit

Otherwise I'll think I'll pass.

Pity - not everything needs a brand to be valuable, don't pass up the opportunity to pick up things by osmosis - it's worth a lot

Regards

But I won't get a shinney new card to put with my otehrs in my wallet.

No worries - I've got one just like it - I keep it next to my donor card in my wallet - that way whoever gets any bits of me gets my overdraft as well

Regards

OMS

LOL

regards

-------------------------
"Take nothing but a picture,leave nothing but footprints!"-------------------------"Oh! The drama of it all."-------------------------"You can throw all the philosophy you like at the problem, but at the end of the day it's just basic electrical theory!"-------------------------

LOL Neither would you be if people were speaking down to you all the time!!

regards

-------------------------
"Take nothing but a picture,leave nothing but footprints!"-------------------------"Oh! The drama of it all."-------------------------"You can throw all the philosophy you like at the problem, but at the end of the day it's just basic electrical theory!"-------------------------